Well perforator shaped charge



April 18, 1961 e. F. TURECHEK WELL PERFORATOR SHAPED CHARGE 2Sheets-Sheet 1 Filed Jan. 3, 1956 INVENTOR. M

April 18, 1961 Filed Jan. 5, 1956 G. F. TURECHEK WELL PERFORATOR SHAPEDCHARGE 2 Sheets-Sheet 2 IN VEN TOR.

' the surrounding formation.

United States Patent ma WELL PERFORATOR SHAPED CHARGE George F,Turechek, Los Angeles, Calif., assignor, by mesne assignments, toBorg-Warner Corporation, Vernon, Calif., a corporation of Illinois Filed12111.3, 1956, SerQ'No. 556,908

5 Claims. Cl. 102- 20 T This invention relates to well perforators, and.particularly to improvements in shaped charge means for producingopenings in well casings and in the surrounding formations to permitentrance of production fluid into the well.

' Well perforating operations have heretofore been acc'omplished usually'by firing one or more solid projectiles or shaped charge jets throughthe casing and into This permits flow of fluid into the casing from thedesired strata in the surrounding formation.

With either the solid projectile or the more recently developed shapedcharge units, a substantially round holeis usually produced through thecasing and extending into the formation; Certain practical limits existon the size of the explosive charge which may be used, and size ofperforation which may be made,;sin'ce' it is usually necessary that theperforation be accomplished without damage tothe explosive carrier, andalso always without permanent damage to the casing. If excessively largecharges are used, the explosive carrierbody and also the casing may beweakened and deformed, or even shattered. I i V With either the solidprojectile or the shaped charge this limitation has sometimes preventedthe'formationof .holes of the size desired by-operat'ors in the field,

from a production capacity standpoint In order to tap larger areas, theoperator may' shoot a .pluralityof charges in a single operation, as isconventional practice, but in view' of the physical limitations on. thespac-T ingot individual charges in a gun, the number of holesper. linearfoot of casing which maybe shot is necessarily limited, and in turn, theeffective perforated area of; the oilproducing formation, iscorrespondingly restricted. I

. Another disadvantage-of the formation of large'ro und.perforationholes residesin the relative freedomzforcn trance of sandinto the well casing which thcy permit.

alsdproducie a linear slot in the casing, which will prevent'theentrance of sand and other particles of a size which would readily passthrough around hole of the same. cross-sectional area and clog up thetubing. The

linearly slotted casing is thusf'rnore effective in screening outundesired material. 1

making possibletheformation of openings in the casing tappinglargerareas without damage to the casing and with given weights ofexplosive; y It' is a further 'object to provide means for producingaalarger drainage area inthe surrounding formation for a givenweightpfcharge. v

,{It f another'object of the invention to; provide means fpr perforatinga greater vertical extent of a particular Figures 1 and r Patented Apr,18, 1961 stratum surrounding the casing for a given weight of shapedcharge units effective to produce a more readily controllable verticallydisposed cutting sheet of gases.

It is still a further object to provide a shaped charge a unit adaptedto produce a linear'jet of limited crosssectional extent in both lengthand width, but of substantially greater velocity and penetrating powerfor a.

given Weightof charge. I

The objects of this invention are accomplished by an improvement in therecently developed shaped charge type of-perforator which makes itpossible to produce a linear slit through the casing of accuratelycontrollable length and width.

The invention, comprises, in brief, an improved form of charge having aV-shaped cavity elongated inv the direction in which the vertical slotis to extend. The gaseous cutting sheet resulting from the explosivecharge is'strengthened in -its' cutting form by the use of a verticallydisposed barrier rod positionedbetwee'n the apical portion of the cavityliner and the booster charge, with the latter also extending parallelto'the means for initiating explosion of the charges. The verticalextent of the slot produced maybecontrolled by limiting it both top andbottom by the charge case itself,-which in some embodiments may bereinforced by relatively heavy metal backup plates extending over thetop and bottom of the charge. An additional control'feature'is offeredin one embodiment of the invention in which the booster charge flaresoutwardly from a central pointin a vertical plane throughthe explosioninitiating ineans iand is terminally shielded therefrom by the case. Instill anviding a charge -liner flaring outwardly in'a vertical plane,

with a portion of the explosive charge extending to the.

open end of the charge both above and below the liner, as well as alongthe sides thereof. These elements are all disposed evenly about an axisof symmetry.-

These andother objects, advantages and features of novelty of theinvention will become more apparent from thefollowing specification,taken together with the accompanying drawing's,-in which:

; Figure 1 isa perspective 'view of a shaped charge unit incorporatingthe. present invention;

Figure 2 is a sectional view of the embodimentta ken along the line'indicated by 2-2 in Figure l;

Figure 3 is a sectional view of the embodiments of 2 taken as indicatedbyline 3 3 in Figure'Z; y 1

Figure 4 is a perspective view of the liner element employed' in theembodin'ients' ofFigures-l to}?! and 5 to 7,

inclusive;

Figure 5 is a sectional view, takenin a plane similar r the. shapedcharge unit of'the invention, takenin a lane Iris thus the primaryobject of this invention to pro-- p a vide improvements in shaped chargeperforating units,

. snt ia indicated 7 7i i u 6; i

Figure 8 is a-sectio nal view of still anothenembodi- 'ment of theinvention, taken a plane indicated byline Figure is a perspective viewof the liner element employed with the embodiment of Figures 8 and 9.The shaped charge unit as illustrated in the drawings is designed to bemounted within a carrier body or gun sealed against the entrance of wellbore fluid under "pressureby frangible ports through which the shapedcharge jets may readily penetrate'to perforate the'casing and theformation surrounding the borehole. The de tails ofsuch agun have notbeen illutrated here since they form no part of the present invention. Asuitable carrier is disclosed in copending application entitled GunPerforator, Serial No. 138,215, filed January 12, 1950, now: Patent'No.2,742,857, to which attention is directed for details of construction.

The shaped charge unit of the invention has been illustrated in apreferredembodiment in Figures 1-4,

inclusive. In these figures is shown a unit, generally designated as 10,formed symmetrically about its longitudinal axis in planes parallel toand normal to substantially planar top and bottom portions. The unit 10has an outer housing 11 formed preferably of frangible ceramic materialproviding rigid support but reducible to very fine fragments whensubjected to the shock like metal into a V-shaped portion about arounded apex 36. The liner is then pressed into the surface of the maincharge 30 by a hydraulic press or other. suitable means of applying evenpressure over the surface thereof. The 'width' of. the slot maybecontrolled by varying the angle of divergence of the liner walls. t

The forward end 32 of the shaped charge unit is open, I I

it being well known to those skilled. in the art that such an open spaceis a requisite from the formation of aproper gaseous jet discharge. Theunit is intended to be so mounted that an adequate stand-off distance isprovided in the gun.

It will be observed that with this construction the apex 36 of the liner34 is parallel to the barrier 26, the booster charge 25 and thedetonator means 22. These elements are all disposed symmetrically abouta plane through the central axis of the shaped charge unit so that acutting sheet of gas will be formed in such projected plane at the openend 32 when the booster chargejis 'initiated'by a detonation wavetraveling along the detohating means 22.

7 When. the Primacord is detonated by well known ini-,

' tiating means, not shown in the figures, it detonates the adapted toreceive explosion initiating or detonator means 22. The detonator meansmay be any readily available commercial detonating fuse such as thatknown, under the trademark Primacord to identify a fuse such as the RDXtype having 98% cyclonite and 2%.wax.

Cycloniteis an abbreviation for cyclotrimethylenetrinh is also used todesignate the PETN type, which is 100% pentaerythrite tetranitrate.-

trarnine. Primacoro A satisfactory concentration is provided by using afuse having 50 grains of either material per foot.

f The transverse rear wall also has formed in the inner portion thereofa rectangular booster seat 24 to which the rounded groove issubstantially tangent. A booster charge is disposed in seat 24 andextends adjacent the Primacord 22 between the top 12 and the bottom 14of the housing 11. 1" V The booster seat 24 may be open in some casesalong a very narrow slot to the detonator means receiving groove 21. Inthe more usual case it is desirable that the housing wall therebetweenbe made very thin, of the order of .0l- -.02 inch. to assist inretaining the booster charge in position, while yetcifering a minimum ofresistance to the transmission of the detonating wave from the Primacordto the booster.

Forwardly'of the booster charge 25 is normally disposed a barrier 26,which may be a substantially cylindrical rodof steel or equivalentmaterial extending between the top 12 and bottom '14.' In the embodimentas" shown; a barrienreceiving recess 27 is formed in the bottom 14,while a bore 29 extending through the. top 12 permits the barrier to beinserted therethrough for assembly with the rest of the case. .After thebooster charge 25 hasbeen placed in seat 24, barrier 26 is inserted andthe main charge chamber 30' filled with the may blesimply and"economically formed by bending a thin flat rectangular strip ofaluminum,-copper orfthe booster charge 25, which in turn initiates themaincharge 31 symmetrically about the beforementioned central plane ofthe case and charge. The presence ofthe barrier 26 tends to slow up theprogress of the shock, waves along the central axis of the device, and,the waves passingon either side thereof will re-combine. or impingeupon one another to produce a centrally directed cutting sheet ofgaseous products having. a velocity greater than would havebeen the casehad the. barrier not been present. j t

In Figure 5 is shown an embodiment, otherwise similarto that in Figures1w 4, except that the booster charge 40 has a'restricted length ofcontact with the Primacord 22 and flares outwardly therefrom, whenconsidered in section through the longitudinal axis of the Primacord, toobtain a more centralizedyinitiation of the booster charge 40 and a moreuniformly timed initiation of the main charge, here indicated as 41. Inthis embodiment, as inthat ofFigures 1 to 4, the presence of the barrier26 is.believed to assist in causing the building up, at lestmomentarily, of a high pressure zone therebehind by the explosivelyproduced gases. The pressures there developed are substantially greaterthan if a barrier had not been present, due to thexrestriction oftheavailable area through which the high velocity detonation waves mayproceed and due to their impingement upon.

one another forward of the barrier. In addition, the buildup isrnademore' even or uniform along the full vertical extent of the charge. Thisis accomplished by the use of a flared booster seat terminallyshortenedby an angularly extending top shoulder 42 and bottom shoulder 44. Theseshoulders provide angular limitations onthe'length of the seat, and actas barriers to shield the top andbottom of the booster and main chargesfrom interference effects from the detonating wave in ad jacentportions" of the Primacord. The result is a more central initiation ofthe booster and main charge, so that the top and bottom portions developtheir full explosionfpressures more nearly simultaneously, therebyincreasing the force, effectiveness and accuracy of thepenetratingaction. j j Another variation in the construction of the embodiment ofFigures 1 to 4 is illustrated insection from the side in Figure .6 andfrom the front in Figure 7. fln

Figures 6 and 7 additional means are disclosed for limit-- ing thevertical extent of the slit produced" Here the top and bottom housingwalls 12 and 14 are reinforced by heavy metal top and bottombarrierplates 51 and 52 respectively which provide additional insurancethat the linear jet will not expand in a directionpa'rallel to thelength of the slit andtothe axis of the Primaco'rd' Another embodimentis shown in Figures 8, 9 and g l in which the advantages of centralinitiation utilized in the embodiment of Figure 5 are retained, togetherwith an alternative method of securing a limitation of the verticalextent of the cutting sheet. It will be seen in Figure 9 that the topand bottom shoulders 42 and 44 respectively are used to shield the maincharge and the booster charge near the top.and bottom ends of the thousing, as in the embodiment of Figure 5. The vertical limitation ofthe cutting jet sheet is obtained, however,

by forming the liner, generally indicated as 45, with a flare toward theopen end along two mutually perpendicular axes. Thus the charge case notonly flares away from the apex 36 in a horizontal plane, as did thatshown in Figures 4 to 7, inclusive, but alsoin a, vertical plane, as maybe seen in-Figures 9 and 10. The liner has not only'side portions 37 and38, as does the form shown in Figures 1 to 7 inclusive, but, inaddition, has a top member 46 and a bottom member 47 extendingdivergingly toward theopen end of the housing, but at a lesser anglethan that of the side portions, as seen in Figures 9'and 10.

With this embodiment the charge body .41 has top portions 49 and bottomportions 50 extending-toward the open end of the housing with the resultthat, when detonated, a portion of the explosive force is directedtoward the center line of the device from the top and bottom portions,and combines with the remainder of the gaseous jet-forming explosiveforces to produce a plaincutting sheet which will be of lesser verticalextent than that of the open end 32 of the housing.

In certain cases, the embodiments of Figures 6 and 7 described above maybe modified by omitting the top and bottom barrier elements 51 and 52and relying, for the formation of a cut-ting sheet of gases of thedesired character, on the means such as those described above in,connection with Figures 8-10 to produce more even detonation.

The embodiments described may also be utilized with guns or carriers ofother than the sealed type by suitable adaptation. For this type ofoperation, usually employed in connection with so-called open holeshooting, the shaped charge units must be individually sealed at theirforward ends to prevent bore hole fluids from entering the charge cavityand so much of the space forward of the charge as is required for properjet formation. Guns or carriers for this type of operation are wellknown in the art, and suitablesealing means which may be utilized inconnection with this invention are disclosed in the pending applicationof Lorrain D. Meddick entitled Debris-free Perforating Gun filed Jan. 9,1956, wit

Serial No. 557,953,

From the above description it will be apparent that I have provided ashaped charge device for cutting linear slits in casing and into thesurrounding'bore-hole formations, which slits may be accuratelycontrolled in their width and vertical extent and may be employed toobtain a much greater area of perforation and drainage than is possiblewith round holes in the casing and the adjacent strata as heretoforeusually employed.

It is to be understood that the foregoing is illustrative only of thebest mode contemplated for accomplishing I the invention, and that theinvention is not to be limited adapted to receive elongated" initiatingmeans; an elongated initiating means in said groove; .a booster'chargedisposed within said housing adjacent saidinitiating.

me'ans;a main charge disposed lwithin said housing; a

parallel to said line of intersection and located between.

said booster and said liner, the ends of said barrier being supported bysaid container; said booster charge being of lesser extent in theportion thereof adjacent and parallel to said initiating means than thevertical extent of said main charge, and expanding symmetrically awayfrom saidinitiating means to intersect with said main charge; saidcontainer being arranged to form barriers between said initiating meansand said expanding portion of said booster charge.

2. A shaped charge perforator unit comprising in combination: acontainer of frangible material having an open end and a verticallygrooved end opposite thereto adapted to receive elongated initiatingmeans; an elongated initiating means in said groove; abooster chargedisposed within said housing adj acent said initiating means; a maincharge disposed within said housing; a recess symmetrically formedwithin said rnain charge having a pair of substantially planar wallsdiverging outwardly toward said open end of said housing, the line ofintersection of the planes of said walls being parallel to saidinitiating means; a metallic liner for said recess; a solid, linearbarrier disposed in said explosive charge parallel to said line ofintersection and located between said booster and said liner, the endsof said barrier being supported by said container, said booster chargeextending closely adjacent said initiating means centrally of saidcontainer and expanding symmetrically away therefrom to intersect saidmain charge adjacent the upper and lower boundaries thereof; saidcontainer extending centrally inward about said expanding portion ofsaid booster charge to-shield it partiallyfrom said initiating means.

3. A shaped charge perforator 'unit comprising in adapted to receiveelongated initiating means; an elongated initiating means in saidgroove; a booster charge disposed within said housing adjacent saidinitiating means; a main charge disposed within said housing; a recesssymmetrically formed within said main charge having a pair ofsubstantially planar walls diverging outwardly toward said open end ofsaid housing, the line of intersection of the planes of said walls beingparallel to said initiating means; a metallic liner for said recess; asolid, linear barrier disposed in said, explosive charge parallel tosaid line of intersection and located between said booster and saidliner, the ends of said barrier being supported by said container, saidbooster charge extending closely adjacent said initiating meanscentrally of said container and expanding symmetrically away therefromto intersect said main charge adjacent the. upper and lower boundariesthereof; said container extending centrally inward between, saidexpanding portion of said booster charge and said initiating means toshield the extremities of said charge partially therefrom.

4. A shaped charge perforator unit comprising in combination: acontainer having a pair of side walls, top and bottom walls transverseto said side walls, and front and rear ends extending in planestransversely of said walls; an explosive charge disposed in saidcontainer; a cavity formed in said charge having a pair of substantiallyplanar'walls extending transversely of the top and .bottom walls ofsaid'container and diverging from each other symmetrically toward thefront end of said con tainer; metallic liner means disposed on said pairof substantiallyplanar walls; a solid, linear barrier disposed in saidexplosive charge extending parallel. toqthe line. of intersection of theplanes of saiddiverging planar walls, said barrier being furtherdisposed rearwardly of the, inner end of said cavity and symmetricallywith respect to the plane bisecting the dihedral angle between saiddiverging planar walls, the bottom wall of said container providing arecess receiving the bottom end of said barrier and the top wall of saidcontainer providing a bore extending therethrough and receiving the topend of said barrier; and means for initiating detonation of said chargerearwardly of said barrier. v

5. A shaped charge perforator unit comprising in combination; acontainer having a pair of side walls, top and bottom walls transverseto said side walls, and front and rear ends extending in planestransversely of said walls; an explosive charge disposed in saidcontainer; a cavity formed in said. charge having a pair ofsubstantially planar walls extending transversely of the top and bottomwalls of said container and diverging from each other symmetricallytoward the front end of said container; metallic liner means disposed onsaid pair of substantially planar walls; a solid, linear barrierdisposed in said explosive charge extending parallel to the line ofintersection of the planesof said diverging planar walls, said barrierbeing further disposed rearwardly of the inner end of said cavity andsymmetrically with respect to the plane bisecting the dihedral anglebetween said diverging planar walls, said barrier extending from the topWall to the bottom wall of said container; means connecting the upperand lower ends of said barrier to the top and bottom walls,respectively, of said container; and means for initiating detonation ofsaid charge rearwardly of said barrier.

References Cited in the file of this patent UNITED STATES PATENTS

